Device for the production of oscillations



Sept. 15, 1936. .1. HAUSSER 2,054,252-

DEVICE FOR THE PRODUCTION OF OSCILLAT IONS Filed July 16; 1934 Patented Sept. 15, 1936 UNETE STATES PATENT OFFICE DEVICE FOR THE PRODUCTION OF OSCILLATIONS Isolde Hausser, Heidelberg, Germany 6 Claims.

My invention relates to a device for the production of oscillations, and more particularly for the production of very short electric waves by means of highly exhausted vacuum valves having a cathode, a grid and a plate electrode and in which a further, auxiliary electrode is arranged between the cathode and the grid and is so positioned, formed and charged that it screens the grid wholly or partly from the electrons emitted by the cathode.

In the development of efficient transmitter valves for very short waves great diiliculties, as is well known, are still to be overcome. The efficiency of the valves hitherto employed is extremely low, particularly if the wave length of the oscillations is reduced to such an extent that the travelling time of the electrons must be taken into consideration. This travelling time may be reduced by increasing the speed of the electrons, for instance, by means of a high positive grid potential. However, in the case of the usual valve type one has to put up with a high loss in employing such an expedient, since a considerable amount of electrons flows directly from the cathode to such a highly positive grid.

The invention has for its object to eliminate the above undesired additional action to which is partly due the extremely low efiiciency of the usual transmitter valves for short waves. With this end in view the gridwhich is to fulfill several conditions inconsistent with one another, i. e., on the one hand, it must be impressed with a high acceleration voltage so as to attain great speeds of electrons and, on the other hand, should not be impressed with a high potential in order to prevent too great losses between cathode and control gridis so to say subdivided into two grids: i. e. a grid with high positive potential which will be denoted hereinafter as acceleration grid and a second grid with low or even negative potential with respect to the heated cathode, the second grid being placed between the acceleration grid and the cathode and representing the control grid proper.

This control grid which is inserted according to the invention between the heated cathode and the acceleration grid must not only be correspondingly arranged as regards space but must also be suitably designed geometrically in order to obtain the desired result: The rods or wires of the acceleration grid must be located, viewed from the heated filament of the heated cathode, behind the rods or wires of the control grid. The stream of electrons emitted by the cathode will be then divided into individual small streams which pass by the rods or wires of the acceleration grid. The control grid acts in a screen-like manner. The electrons flow, therefore, with great velocity through the interstices between the acceleration grid elements in accordance with high acceleration potentials. Further, the voltage effect of the acceleration grid past the control grid bars and toward the cathode must be as great as possible in order that the electrons may attain great velocities on their way from the cathode to the acceleration grid, in order to maintain the magnitude of the required acceleration voltages within reasonable values.

Besides the above-known conditions, i. e., the guard-like protection of the acceleration grid by means of the control grid and the great acceleration voltage effect of the acceleration grid, the other usual requirements are to be met; for

instance maintenance of the geometrical distances, and thus of the travelling times of the electrons at a minimum value. To this end, the heated filaments of the cathode are preferably arranged elosely in front of the interstices between the grid rod elements. Consequently, the rods of the acceleration grid must be laterally protected by the elements of the control grid, i. e., the latter must form so to say a roof for the former.

The transmitter valve provided in the abovedescribed manner with a control grid for deviating the electrons into the interstices between the acceleration grid may be employedin various connections. For instance, the plate in the form of a disc, and serving as fourth electrode and lying beyond the acceleration grid, which plate in the case of a concentric arrangement of electrodes may also be replaced by a cylinder, may be caused to act as anode, i. e., it may be impressed with a high positive potential. Such a connection which is usually employed for the production of waves of considerable length could not be utilized for short waves to the desired extent. However, the novel valve has the advantage, that the acceleration grid for the electrons operates at zero current, i. e. without losses, owing to the screening effect of the control grid. For this reason, the efficiency of the valve is considerably increased. The plate may be impressed with a positive voltage which has a value below that of the acceleration grid as is the case in the known dynatron connections. Also in this case an advantage is ob tained in that the acceleration electrode works nearly at zero current owing to the screening effect of the control grid.

7 The advantage of the novel transmitter valve,

i. e., that the acceleration grid operates practically at zero current, is of particular importance in connections, in which the plate electrode is impressed with high negative potentials or with zero potential with respect to the cathode, in which case this plate acts as retarding electrode. In that case the acceleration grid serves as anode. Such a connection is illustrated in the accompanying drawing in which Fig. 1 represents in diagramdrically shaped and surrounds the concentrically reach the zone of zero potential.

a potential of about 106l volts. 7 emitted by the cathode shoot under the action of arranged grids and cathodes. Such an arrangement is particularly suitable for the production of centimeter waves.

Referring to Fig. l, the heated filaments of the cathode are denoted by K, the acceleration grid by G2, the control grid by G1 .andthe plate electrode by A. The relative arrangement of the electrodesand their geometrical design are shown in semi-diagrammatic fashion. In front of the individual rods or wires of the acceleration grid viewed from the cathode plane are positioned the individual broader strips of the control grid which, for instance, have an angular form so that they partly embrace the rods or wires of the acceleration grid. The heated filaments of the cathode are positioned in the interstices between the control grid strips, so that all travelling distances become small. The control grid maybe impressed with respect to the cathode for instance with a negative potential of 500 volts, the acceleration grid with .a positive potenial of 4000 volts and finally the plate A serving as retarding electrode may in turn be impressed with a negative potential with respect to the cathode, i. e., with The electrons the static fields through the interstices between the control grid G1 and those between the acceleration grid G2 into the space between the acceleration grid G2 and the plate electrode A. In this space they meet a strong field owing to the strong negative charge of the plate electrode. The speed of the electrons is reduced to zero owing to the retarding effect of the plate field as soon as they 7 The location of this zone is identical with that of plate A if'the latter has'the potential zero with respect to the cathode and is located further toward the acceleration grid G2 if the potential of the plate, as

assumed in the embodiment shown, is negative with respect to the cathode. As soon as the electrons attain the velocity zero, their direction of flow is reverseddue to the influence of the positive voltage applied to the acceleration grid G2 and the electrons impinge on the rods or wires of thisgrid at full speed. The rhythmical reversal of such a cloud of electrons causes, for instance, at the acceleration grid G2 fluctuations of voltage in the same rhythm, particularly when the oscillation circuit connected to the acceleration grid and the cathode or also to the acceleration grid and plate electrode is substantially in resonance with the movements of the cloud of electrons, i. e., when the duration of an oscillation of the oscillation circuit is approximately equal to the time which the cloud of electronsrequires to move forward and return.

As an oscillation circuit a pair of parallel conductors is'preferably employed, one end of which pairis respectively connected to the appertaining electrodes of the valve and the other end is bridged tween the cathode and control grid G1.

by a blocking condenser capable of being'shifted along the parallel conductors for the purpose of tuning. In the drawing these parallel conductors are designated by L1L1 and LzLz, and the appertaining condensers are denoted with C1 and C2 respectively. The direct-current connections lead to the blocking condensers by way of reactors Dr. Also the other direct current connections lead as usual to the cathode and retarding electrode through reactors Dr.

As soon as the alternating electro-motive force is produced and superimposed on the electrode direct-current voltages it controls the flow of electrons. Both oscillation circuits formed of the parallel conductors as main part are coupled by the common inner capacity of the valves be- The parallel circuit L1L1 is closed through said capacity. The other circuit L2L2 is series-connected with two capacities, i. e., with the above-mentioned capacity between the cathode and the control grid and with the other between the control grid G1 and acceleration grid G2, so that the system L1L1 is coupled with a portion of the capacity of circuit L2L2. The alternating voltages between the acceleration grid and cathode .and between the control grid and cathode are in phase.

As soon as the oscillation circuit has been afiected, as in any oscillatory valve circuit, by an impulse, the oscillation process is as follows: In the positive phase of both grid alternating potentials the electrons which are so accelerated by the strong field as to obtain a high speed, are forced in the above-mentioned manner through the grid interstices into the space between the acceleration electrode G2 and plate electrode A and .are here retarded to the velocity zero. In the negative phase of both grid alternating potentials the electrons, on the one hand, change their direction of motion in the retarding space and impinge upon the rods or wires of the acceleration grid G2 which acts here as anode; on the other hand, since, as above stated, the alternating potential applied to the control grid also passes through the negative phase, the flow of electrons from the cathode through the interstices of the grid is considerably weakened in the direction toward the retarding electrode so that an interference by newly emitted electrons with the cloud of electrons returning from the retarding field to the acceleration grid is avoided. The negative resistance of the valve, required for setting up the oscillations, is brought about by the fact that the electrons in the positive phase of the alternating potential pass by the acceleration grid at a very high speed and impinge upon the grid as anode current only after they have been retarded and have changed their direction and at a time when the alternating potential at this grid just passes through the negative phase. 7

The above-described connection may also be, of course, employed for a concentric arrangement of the electrodes as shown in Fig. 2.

It is also possible to connect the parallel conductor circuit on the one hand to the retarding electrode and acceleration grid, and on the other hand to the retarding electrode and the control grid.

I claim as my invention:

1. Arrangement for producing electrical oscillations including a highly evacuated envelop containing a cathode, a plate, an acceleration grid interposed between said cathode and plate and a control grid'interposed between said cathode and acceleration grid, circuit connections for charging said acceleration grid highly positive with respect to said cathode and charging said control grid with respect to said cathode at a potential lower than said acceleration grid potential and said plate at a potential not higher than neutral with respect to said cathode, a tunable oscillatory circuit including said acceleration grid, and means for imparting oscillations to said control grid which are substantially in phase with the oscillations prevailing at said acceleration grid.

2. Arrangement for producing electrical oscillations including a highly evacuated envelop containing a cathode, a plate, an acceleration grid interposed between said cathode and plate and a control grid interposed between said cathode and acceleration grid, circuit connections for charging said acceleration grid highly positive with respect to said cathode and charging said control grid with respect to said cathode at a potential lower than said acceleration grid potential and said plate at a potential not higher than neutral with respect tosaid cathode, a tunable oscillatory circuit including said acceleration grid, and means for imparting oscillations to said control grid which are substantially in phase with the oscillations prevailing at said acceleration grid, the grid elements of said acceleration grid being respectively in alinement with the control grid elements with respect to the direction of the electron stream emitted from the cathode, so that the acceleration grid is located in the electron shadow produced by said control grid.

3. Arrangement for producing electrical oscillations including a highly evacuated envelop containing a cathode, a plate, an acceleration grid interposed between said cathode and plate and a control grid interposed between said cathode and acceleration grid, circuit connections for charging said acceleration grid highly positive with respect to said cathode and charging said control grid with respect to said cathode at a potential lower than said acceleration grid potential and said plate at a potential not higher than neutral with respect to said cathode, a tunable oscillatory circuit including said acceleration grid, and means for imparting oscillations to said control grid which are substantially in phase with the oscillations prevailing at said acceleration grid, the grid elements of said acceleration grid being respectively in alinement with the control grid elements with respect to the direction of the electron stream emitted from the cathode, and being at least partly surrounded by said control grid elements, so that the acceleration grid is located in the electron shadow produced by said control grid.

4. Arrangement for producing electrical oscillations including a highly evacuated envelop containing a cathode, a plate, an acceleration grid interposed between said cathode and plate and a control grid interposed between said cathode and acceleration grid, circuit connections for charging said acceleration grid highly positive with respect to said cathode and charging said control grid with respect to said cathode at a potential lower than said acceleration grid potential and said plate at a potential not higher than neutral with respect to said cathode, a tunable oscillatory circuit including said acceleration grid, and means for imparting oscillations to said control grid which are substantially in phase with the oscillations prevailing at said acceleration grid, the grid elements of said acceleration grid being respectively in alinement with the control grid elements with respect to the direction of the electron stream emitted from the cathode, so that the acceleration grid is located in the electron shadow produced by said control grid, said cathode consisting of a plurality of elements disposed in alinement with and close to the interstitial spaces between said control grid elements.

5. Arrangement for producing electrical oscillations including a highly evacuated envelop containing a cathode, a plate, an acceleration grid interposed between said cathode and plate and a control grid interposed between said cathode and acceleration grid, circuit connections for charging said acceleration grid highly positive with respect to said cathode and charging said control grid with respect tosaid cathode at a potential lower than said acceleration grid potential and said plate at a potential not higher than neutral with respect to said cathode, a tunable oscillatory circuit including said acceleration grid and said cathode, and a second tunable oscillating circuit including said cathode and said control grid, for imparting oscillations to said control grid which are substantially in phase with the oscillations prevailing at said acceleration grid.

6. Arrangement for producing electrical oscillations including a highly evacuated envelop containing a cathode, a plate, an acceleration grid interposed between said cathode and plate and a control grid interposed between said cathode and acceleration grid, circuit connections for charging said acceleration grid highly positive with respect to said cathode and charging said control grid with respect to said cathode at a potential lower than said acceleration grid potential and said plate at a potential not higher than neutral with respect to said cathode, a tunable oscillatory circuit including said acceleration grid, and means for imparting oscillations to said control grid which are substantially in phase with the oscillations prevailing at said acceleration grid, the distances between aforesaid electrodes and the potentials-applied to them being selected with respect to the frequencies of the oscillations imparted to said two grids such that accelerated electrons which are reversed in their original path by the prevailing plate potential strike the acceleration grid during the descending portion of each half period of the alternating electromotive force applied to said grid.

ISOLDE HAUSSER. 

